Truck loading docks along an exterior wall of a building typically comprise a doorway by an elevated platform so that when a truck or trailer backs up to the doorway, the cargo-supporting bed of the truck is approximately flush with the platform. Many loading dock platforms have a dock leveler with a vertically adjustable front edge to compensate for moderate height differences between the platform and the truck bed as well as provide a bridge-like path between the platform and the truck. Some loading docks also include a vehicle restraint that helps hold the truck at the dock while cargo is being transferred to and from the truck. For safety, loading docks might also include some type of retractable barrier that can extend across the doorway. Examples of such dock levelers, vehicle restraints and/or retractable barriers are described in U.S. Pat. Nos. 8,087,443; 7,380,375; 7,337,822; 7,207,370; 7,032,267; 6,880,301; 7,841,823 and 6,431,819, all of which are hereby incorporated herein by reference in their entireties.